A Bard's Guide to Crossbreeds

Here is an article to answer questions on every bard's mind;

What will be the aftermath of my "endeavours"?

To answer this question one must first identify what type of species one is, and what type of species your mate is. For your consideration the following types exist:

• Mammalian
• Reptilian
• Insectoid and Anthropod
• Amphibian
• Avian
• Fey

If both you and your mate belong to a different type, then you're in luck and probably won't have to bother with pesky child support and such. If you are the same however there is a 75% chance that the child will belong to the mother's species with some minor traits inherited from you. And a 25% chance of the inverse. At least in most cases, however, we will be going through a list of exceptions.  

The Blood is Strong

Some species have considerably more persistent blood than others, these species are known for there half-bloods. A common example is orcs, the blood of an orc is strong, as such if a male orc were to mate with a human female. The result is 25% of being a full-blooded orc, and 75% chance of a half-orc (and vice versa if the sexes were switched). As this example shows, strong blooded species drown out the possibility of having the child belong to the weak blooded parent's species.
However, I hear you ask, what about the case of two strong blooded species, preforming the act of reproduction? To answer this question lets look into another example, a female elf and a male tabaxi. In this case, there is a 75% chance of a half-elf and 25% chance of a half-tabaxi. Once again the female half is slightly more dominant than the male one. But there is no chance of a full-blooded child being born of such a union.
Hereby I give you a list of strong blooded species to consider:

• All elves -> Half-Elves
• Orcs -> Half-Orcs
• Ogres -> Half-Ogres
• Tabaxi -> Half-Tabaxi
• Cambions -> A Tiefling depending on the Cambion's Origin.
• Rakshasa -> Rakshasa Tiefling
• Geni -> Genasi

Ogres and Orcs

The combination of these two strong blooded always results in an Orog.  

Return to roots

If a half-blood mates with a full-blood of the same strong blooded species. The offspring is full blood.
If two half-bloods of the same species mate, there is a 1/4 chance that the offspring will be full blood, otherwise it will simply remain a half-blood.

Exceptional cases

Whereas the lines spoken above hold true for most species, there are a few exceptions that can result in a child surprise after all.

Dragons

Many dragons possess the ability to shapeshift into the guise of a humanoid. Doing so will make them genetically compatible with the species they shift into. However, the child of such union almost always results in a Half-Dragon with some trait of the other species. Except for the case of A Dragon and a Dragonborn, in this case the offspring will simply use the above rules to determine where the child will be a Dragon or a Dragonborn.
Another thing to note in regards to Dragons is to consider who takes the male and female roles. For a nonreptilian female that gets impregnated by a polymorphed Dragon might find that their womb is forever changed from having to lay such a majestic egg.  

Succubi/Incubi

Succubi and Incubi possess the uncanny ability to impregnate and be impregnated by any humanoid. Such a union will always result in the birth or hatching of a Cambion. It remains uncertain what will happen if one were to cross a Succubi and a Dragon. There has yet been a succubus that has seduced a dragon, as far as we know.
Aside from this, it is said that other demon & devil affairs with humanoids also result in Cambions, The lustful Succubi and Incubi are by far the more likely candidates for such a union.  

Tiefling

Tieflings themselves come to be through a variety of manners described in their own article. And this manner heavily influence how their line progates. For example, some devil pact born Tiefling only appear in a bloodline once every thousand years as part of the price of the pact. Others like Rakshasa tieflings often follow standard genetic-based on their heritage.  

Changelings and Doppelgangers

The Changelings and Doppleganers follow the rules of whatever species they morph into. With the addition that at puberty there is about a 50% chance for the child to discover they have the Changeling's or Doppelganger's gifts.
Noteworthy, if changelings offspring is of a different size category then itself, the offspring will never be a changeling. Doppelgangers are not subject to this restriction.  

Goblinoids

Due to their nature, goblinoids skew the change of getting a goblinoid offspring in their favour. They always have 75% chance of getting a goblinoid offspring, regardless of what sex they take in the relationship.
When dealing with strong blooded species, it still favours the strong blooded ones, except for the case of elves. There Goblinoid blood is favoured.  

Orcs and Elves

Due to there strange historic relation, and the nature of orc blood. This relation should be treated as an orc with a non-strong blooded species.  

Fey Inter compatibility

Humanoid Fey can produce offspring with any Mammalian humanoid.
Mono-sex species like Satyrs, Nymphs and Dryads will have the offspring that matches their sex be of their species, regardless of other things.
It unknown whether Hags can crossbreed, since they normal reproduce Asexually by eating other species babies.  

Geni

Be another shape changer, Geni's can crossbreed with many except some of the other exceptions.
Their children are always Genasi.  

Genasi Heritage

A Genasi's ability to crossbreed depends on its origin. For example, a Genasi born of a Dragonborn and Geni can crossbreed with all reptilians and retrains some appearance of that species. Same for other.  

The Parasidic Neogi

Another exception are The Monstrous Neogi, due to there completely alien manner of reproduction. First off the Neogi do not have a difference between a male and female among there own kind. Instead to infectiously lay eggs inside of their oldest members, to have the children hatch and devour him outright. In the rare case that they do seek out other humanoids for reproduction, they are treated similarly, as that the beast is led inside them like an infection, to the devour the host upon hatching. Despite the general compatibility with all through this method, the Neogi seem to have an unexplainable preference for using females of other species rather than males.